This invention relates to antennae for portable telephones.
Because of their ever-decreasing cost, portable telephones are on the way to becoming widely used by large segments of the population. Also, along with the decrease in cost of operation, existing users have significantly increased their usage. Thus, ever larger segments of the population are making more and longer telephone calls using portable telephones.
Most portable telephones in use today operate using at least one of the following transmission technologies: TDMA (time division multiple access) GSM (Global System for Mobile Communications), CDMA (code division multiple access), PCS (personal communications service) or analog. Commonly used with all of these transmission technologies, however, are non-directional helical or monopole type antennas. Such non-directional antennas are characterized by the fact that they transmit and receive electromagnetic energy more or less equally in all directions. This has at least two disadvantages. First, such antennas are inefficient at transmitting and receiving electromagnetic energy to and from the base station(s). Second, such antennas transmit electromagnetic energy into the body of the portable telephone user, where it must be dissipated as heat, resulting in decreased power efficiency.
Fading is a problem common to most mobile communication systems. Fading occurs when, due to reflections from a plurality of base stations, the incoming waves cancel each other out. This results in a temporary loss of data and, possibly, a termination of the call.
In view of the foregoing, it would be desirable to provide a portable telephone which is efficient at transmitting and receiving electromagnetic energy to and from the base station(s).
It would also be desirable to provide a portable telephone with reduced levels of electromagnetic energy transmitted into the body of the portable telephone user.
It would be desirable to provide a portable telephone with increased immunity to fading.
It is an object of the present invention to provide a portable telephone which is efficient at transmitting and receiving electromagnetic energy to and from the base station(s).
It is also an object of the present invention to provide a portable telephone with reduced levels of electromagnetic energy transmitted into the body of the portable telephone user.
It is another object of the present invention to provide a portable telephone with increased immunity to fading.
These and other objects are accomplished by providing a portable telephone which includes a directional antenna. The directional antenna is designed such that it can be positioned for use so that its beam is substantially parallel to the direction of received electromagnetic energy (i.e., along the horizon), thereby increasing the efficiency at which electromagnetic energy is transmitted to and received from the base station(s) as well as reducing the levels of electromagnetic energy transmitted into the body of the portable telephone user.
In addition, a portable telephone with two directional antennas is provided. The two directional antennas can be positioned for use to provide directional diversity, space diversity or both, thereby providing improved diversity system performance that leads to a reduction in the effects of fading.